We propose experiments designed to solve several fundamental problems in vitamin B-6 catalysis. This coenzyme is known to catalyze many different types of reactions of amino acids. Model systems are suggested which impose specific conformations upon the pyridoxal -- schiff base reactant and dihydropyridine intermediate. Our principal object is to learn how reaction selectivity can be imposed on the coenzyme by a given type of enzyme and to make a semiquantitative measurement of the importance of coenzyme-schiff base conformation upon reaction rate. The elimination of electronegative substituents such as phosphage and sulfate from the Beta-carbon atom of amino acids will be studied in 1:1 and 2:1 complexes of the vitamin b-6 schiff bases with transition metal ions. The bonding in 1:1 complexes will force a series of fixed conformations about the amino acid gamma-carbon atom as the metal ion is varied. Racemization of vitamin B-6 schiff bases formed with aspartic acid, glutamic acid, lysine, ornithine, and 1,4-diaminobutyric acid will be studied structurally and kinetically in metal complexes where the schiff base gamma-carbon atom is held in fixed but different geometries. These studies are designed to reveal how reactivity depends upon orientation or, alternatively, whether stereoselectivity may be obtained by control of the dihydropyridine structure. Vitamin B-6 schiff base complexes of metal ions which are substitutionally inert may be synthesized as isomers with their gamma-carbon atoms fixed in various different conformations. The Beta-hydroxy amino acid aldolase reaction will be studied in these systems. Reactivities and structures of molecular complexes of the vitamin B-6 schiff bases will be studied. Kinetic studies will be carried out to learn whether the partial charge donation to the schiff base or withdrawal from the dihydropyridine can be effective in catalizing or controlling these reactions. Structural studies will determine the sites of interaction.